The objectives of this project are to determine the actions of streptolysin-O on neutrophilic leukocytes and lymphocytes in order to learn whether this toxin plays some role in the pathogenesis of streptococcal infections or their non-suppurative complications (rheumatic fever, glomerulonephritis). Any effects on leukocyte function will be further studied to determine the mechanism of action. The goal for the next year is to investigate the effect of streptolysin-O on in vivo immunologic behavior. Initial studies will be to compare the serum antibody response to a primary antigenic stimulus when the antigen is given alone or in combination with streptolysin-O. If streptolysin-O alters the immunologic response of an animal it will increase the probability that it is an important factor in the pathogenesis of streptococcal infections. Also planned is a quantitative comparison of the interaction of streptolysin-O and phytohemagglutinin. By studying a wide range of streptolysin-O and phytohemagglutinin concentrations, it is hoped that the type of interaction between these two molecules and the lymphocyte can be more firmly established.